The present invention relates to a farm machine comprising a connecting means, intended to be connected to the three-point hitch of a motor vehicle, and a body connected to the connecting means with a first joint having an upwardly directed axis. The body comprising at least one work element driven by a movement gear transmission device which comprises a first housing which is rigidly connected to the connecting means and which comprises an input shaft, and a second housing which is connected in rotation with the body and which comprises an output shaft extending in the direction of the body.
A mower of the present invention comprising a cutting mechanism and a hitching structure is known in the related art. The hitching structure is connected at its front part to the three-point hitch of a tractor. The cutting mechanism consists of a beam supporting several drums which each rotate around a vertical axis. At one of its longitudinal ends, the beam is connected to the hitching structure by a pivot joint having a vertical axis which allows a pivoting of the cutting mechanism of about 180.degree. relative to the hitching structure. The cutting mechanism can be pivoted in particular from a first work position which is to the right of the tractor and in which its longitudinal axis extends perpendicularly to the direction of work, up to a second work position which is to the left of the tractor and in which its longitudinal axis also extends perpendicularly to the direction of work. At its other longitudinal end, the beam is equipped with a support by which the cutting mechanism rests on the ground.
The driving in rotation of the drums of the cutting mechanism is performed from the power takeoff of the tractor which drives, by a Cardan shaft, the input shaft of a housing connected to the hitching structure. This input shaft extends in the direction of advance of the tractor and transmits the rotation movement, by a first bevel gear pair, to a first transmission shaft. The latter has its axis of rotation which is merged with the vertical axis connecting the cutting mechanism to the hitching structure, and transmits the rotation movement, by a second bevel gear pair, to a second transmission shaft. The latter extends inside the beam of the cutting mechanism and drives the drums by a bevel gear pair joined to each drum.
Because of such a movement transmission device, the cutting mechanism can be driven in all the positions in which it can be pivoted around the vertical axis connecting it to the hitching structure.
The advantage of this movement gear transmission device is twofold to the extent that not only does it make possible the driving of the cutting mechanism in all its positions, which is very practical and prevents false maneuvers, but it is also a gear transmission, therefore a transmission which is efficient.
However, this mower encounters several difficulties when it has to pass over the obstacles that the terrain can present. Actually, since the cutting mechanism is connected to the hitching structure by a pivot connection with a vertical axis and since the hitching structure is connected to the three-point hitch of the tractor, it is almost impossible for the cutting mechanism to adapt to the contour of the terrain.
As a result, as soon as the cutting mechanism is brought to move in height, the drums run the risk of clogging or striking the obstacles that the terrain can present.